Method of wood particles orientation

FIELD: wood working industry.

SUBSTANCE: according to the method of wood particles orientation rotation speed of even rolls is determined depending on rotation speed of uneven rolls, the distance between disks and their diametre due to that particles received rotational motion from the disks rotating with different speed go in a chip mattress with minimal orientation angle during fall.

EFFECT: quality increase of wood particles orientation and hardening of reconstituted particle board made of oriented particles.

2 dwg, 1 tbl

 

The invention relates to woodworking industry and can be used in the production of chipboard.

The known method the orientation of the wood particles, including the filing of cutting disks mounted on a rotating rolls. The disks form the intermediate overlap, the distance between the disks is less than the length of the oriented particles, so the particles are expanded and pass between the disks, rolling on the forming conveyor (conveyor) in the direction of orientation [Leonovich A. Technology of wood-based panels: innovative solutions: Textbook. the allowance. - SPb.: Hemostat, 2005, - 208 C., str-126].

A known method of mechanical orientation of wood particles, including the filing of a chip on a thin disks mounted on rollers in staggered overlapping. The drive rolls individual with stepless speed control. Wood particles fall between the discs and placed in a bonded carpet, and 60% of the chips have the angle from the direction of ±15° [Schwartzman G.M., Generously D.A. Manufacture of chipboard. 4th ed., Rev. and supplementary): genre differences. prom the terrain, 1987. - 320 S., str-214].

In the known methods of wood particles receive torque from rotating with different speeds drives the odd-numbered and even-numbered rolls and go with discs under the initial angle αsub> begrelative to the direction of orientation. During the fall prior to forming conveyor particles takes place on the angle αpand placed in a bonded carpet at an angle α (orientation angle), which is determined from the expression: α=|αbegαp|. With decreasing angle α the strength of the finished plates increases, approaching the strength of the original wood [Potashev PU, Lapshin YG Mechanics of wood-based panels. - M.: Genre Differences. prom the terrain, 1982. - 112 S., p.52]. In the ideal case, the angle α is equal to zero. In the known methods in the random setup of the speed of rotation of the rolls is not the condition |αbegαp|=0, i.e. reduced quality orientation.

The known method orientation implemented in the device for orientation of wood particles, including the filing of cutting disks mounted in staggered overlapping on odd and even rolls rotating at different speeds [patent Sweden No. 463627, MCL5B29J 5/04. Spridarhuvudforsedd spridningsanordning för sprinding av en spänmaterialmatta. 1985].

The disadvantage of this method is that the speed of rotation of the even and odd rolls are random, not related in a certain ratio, so the angle of orientation of the wood particles α increases, which leads to loss of strength of manufactured boards.

The invention solves the problem of increasing quality is rantatie wood particles.

The technical result from the use of the invention is to improve the quality orientation by minimizing the angle of orientation of the wood particles, which increases the strength of manufactured wood fibre boards.

This is achieved in that in the method the orientation of the wood particles, including the filing of cutting disks mounted in staggered overlapping on odd and even rolls rotating at different speeds, according to the invention the speed of rotation of the even-numbered rolls ω2set according to the formula:

where ω1- speed rotation odd rolls, rad/s;

h - the distance between adjacent disks odd and even rolls, m;

D is the disk diameter, m

The inventive method the orientation of the wood particles is setting the speed of rotation even-numbered rolls depending on the speed of rotation of the odd roll, the distance between the disks and their diameter, which accounts for the particle receiving rotation from rotating with different speeds of disks in the process of falling are placed in a bonded carpet with a minimum angle of orientation.

The drawings show a fragment of a device that implements the method of the orientation of the wood particles: figure 1 is a top view, figure 2 - side view.

The formula for the speed of movement of the guide body, which is the most p is LNA the orientation of the particles, derived by the author for the first time.

The initial angle at which the escape of particles from the disk depends on the length of the particles and the distance between adjacent disks odd and even rolls:

where h is the distance between adjacent disks odd and even rolls (step orientation), m;

l is the length of the oriented particles, m

In modern orienting devices step orientation h set in accordance with the length of the oriented particles l to execute the optimal ratio h=l/2 [see, for example, carpenters S. M. Improving orientation of the chips in the production of wood-based panels. // Wood-working industry. - 2007. No. 5. - P.4-6], which focuses the maximum amount of wood particles without clogging the device. Then αbeghas a value of 30°. At the time of separation, the particle acquires a speed:

where V1V2respectively the linear velocities of the odd and even rolls during their contact with the wood particles, m/s the Average time of fall of the particles:

where g is the acceleration of gravity, m/s2;

D is the disk diameter, m;

d1- the distance between the upper end of the disk and the average level of similarity with disks of wood particles, m;

d2distance from n the life of all drive up to the surface bonded carpet, m

In modern forming machines distance d2set a minimum and the particles are on average begin fall not from the upper ends of the disks, and somewhat lower (level Assembly), since the disks are set to overlap. The value of d1and d2equal and compensate each other, so in further calculations ignore them.

After a turn and pass between the disks for the fall time t of the particles takes place on the angle αp:

Taking into account (2), (3) and d1=d2the expression (4) has the form:

For maximum orientation of the particles, in which the orientation angle α=0, must satisfy the condition: αbegp. Equating the expression (5) αpbeg=30°, we get the linear velocity of the odd drive is relatively even (m/s)at which the angle of orientation of particles in minimum:

Considering g=9,81 m/s, we obtain:

Expressing the linear speed of odd and even drivesget the angular velocity of rotation of the respective rolls (rad/s):

The ratio of 1.64 in equation (7) and 3,28 in equation (8) have the dimension with the-1·m1/2.

Formula (8)connecting the rotation speed of the even and the wick is the shaft of the rolls, step orientation and diameter disks, derived by the author for the first time.

Air resistance practically does not change the ratio of 3.28 in the expression (8). Taking into account the air resistance oriented particle falls to laying in the carpet a little longer, i.e. must be deployed at a greater angle α. However, the air resistance will prevent the spread of the particles. Thus, increasing the angle α due to a longer drop is compensated by the decrease of this angle due to the smaller spread.

The way the orientation of the wood particles is as follows.

Odd rolls (1, 3, ...) orienting device rotates with angular velocity ω1(rad/s), even the rolls (2, 4, ...) - with speed ω2defined by the formula (8). For example, if ω1=5 rad/s (47,75 rpm), h=0.05 m and D=0.16 m get ω2=7,56 rad/s (72,20 rpm).

Wood particles are fed to the disks. Due to the difference between the linear velocities of the odd and even drives particles acquire torque, and along the rims of their angle relative to the direction of orientation is constantly decreasing, the particles fall between the discs and deployed prior to their placement in the bonded carpet. During the rotation of the even-numbered drive with optimal speed determined from the expression (8), the particles have a minimum angle of orientation.

An example of what westline way

Wood chips from the supply conveyor serves on the disks, the ratio of the angular velocities of the rolls which is determined by the formula (8). Of oriented so chips on the forming conveyor to receive a single layer of bonded carpet, which is divided into briquettes and pressed. It was made three parties single layer of chipboard with thickness of 10 mm from pine shavings, having an average length of 100 mm (0.1 m). The height from the lower ends of the discs with a diameter of 0.15 m to the surface of the formed strand carpet was 0.02 m, the distance between adjacent disks (step orientation) - 0,05 m

The optimum speed of rotation even-numbered rolls were calculated according to the formula (8):

The speed of rotation of the even-numbered rolls with individual actuators were asked 5 rad/s, odd in various parties - 6 rad/s, 7,6 rad/s and 9 rad/S. the Measurement of the angles of deflection of the particle relative to the direction (axis) orientation was conducted for all the fully-visible particles on the upper and lower surfaces of the plates on arbitrary parts of the plates with an area of 200 x 200 mm with the help of protractor. The measurement error was 1%.

Average results of 10 measurements are presented in table 1.

Weighted average orientation angle αcfwas determined as the sum of the average inclination angles αi the fraction of particles γion the plot:

For example, for ω2=6 m/s:

αcf=4,5·0,17+14,5·0,45+24,5·0,21+34,5·0,11+45·0,06=18,9 [deg].

Table 1
The limits of deviation of the particle from the axis orientation, deg.The average angle of deviation αithe hail.The fraction of particles at site γi, %
ω1=6 rad/sω2=7,6 rad/sω2=9 rad/s
0-94,5176112
10-1914,5452142
20-2924,5211223
30-3934,511414
40-50 45629
Weighted average orientation angle αcfthe hail.
18,911,021,1

The experimental results show that the smallest average angle of orientation of the particles have a plate formed with angular velocity even rolls close to that calculated by the formula proposed by the author.

The invention improves the quality of the orientation of wood particles and to increase the strength of chipboard from oriented chips (OSB plates).

The way the orientation of the wood particles, including the filing of cutting disks mounted in staggered overlapping on odd and even rolls rotating at different speeds, wherein the speed of rotation of the even-numbered rolls ω2set according to the formula:

where ω1- speed rotation odd rolls, rad/s;
h - the distance between adjacent disks odd and even rolls, m;
D is the disk diameter, m



 

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